Posted 08 June 2012 - 11:27 AM
If your light has come on then there should be a code stored, so providing that you haven't had codes cleared then yes the dealership will be able to diagnose even without lights. This will save you replacing parts that may not be bad. I don't care for paying for diagnosing myself but most times it pays off to pay this fee once and replace proper parts than to "pay" for time spent on wrong parts being replaced.
2006 GMC Sierra, 1500, SLE 2, Crew Cab, Short Bed, Z71, 5.3L (L59), 4L60e, 3.42 gears, G80, Auto Trac 4x4, Midnight Blue Metallic, Truxxx leveling kit, K&N air filter, Line-X bed liner, Tekonsha brake controller, Firestone Destination LE2 tires, Monroe Relfex Shocks, Trail FX side steps. 100,000 mile club! Have Fun and Enjoy the Reading!